1. Field of the Invention
The invention is in the field of photocopy machines and copier/duplicator machines which have multiple modes of operation. In particular, the invention pertains to copier/duplicators having a chain feeding mode of operation for making copies of documents successively fed into the machine.
2. Description of the Prior Art
Multi-mode copier/duplicator machines are known in the prior art and may, for example, utilize fixed and movable optical systems for operation in different modes such as a BASE Mode and Large Document Copying (LDC) Mode, respectively. In the BASE Mode of operation, documents up to 81/2 .times. 14 inches may be copied, whereas in the Large Document Copying Mode, documents up to 18 .times. 14 inches may be copied. An example of such machines is described in detail in copending application Ser. No. 367,996, filed June 7, 1973, and Ser. No. 528,163 filed Nov. 29, 1974 (D/73383C). In such machines, it is advantageous to reduce the time at which subsequent copies of original documents may be fed into the machine so as to achieve a faster chain feeding mode of operation particularly when the most utilized small documents (81/2 .times. 11 inches) are employed. However, with multi-mode machines which copy both large and small documents, it has been a problem to reduce the time between successively fed "small" documents, and, to utilize the same control circuitry for large documents which, of necessity, require longer times for the xerographic and bookkeeping functions to take place. In these prior art machines, a single, master counter, controlled all of the pertinent xerographic functions including charge, exposure, development, fusing, jam detection, and billing. It has thus been necessry to wait for all of these pertinent functions to be initiated and/or completed before a subsequent document original could be processed. In effect, copier/duplicators utilizing a small paper cassette for 81/2 .times. 11 inches copies would be strapped to the same time constraints imposed for large document sizes. As a consequence, substantial time is wasted, particularly in waiting for the jam sensing and billing functions to be completed.